1. Field of the Invention
The present invention relates to an article transport facility, and more specifically to an article transport facility including a plurality of article transport vehicles configured to travel along a travel path defined by one or more rails installed to the ceiling and wherein the travel path includes a primary path forming a loop and secondary paths, each arranged to extend by at least one article transport location, and a first connecting path connecting the primary path and a secondary path for allowing article transport vehicles to travel from the primary path to the secondary path and from the secondary path to the primary path, the secondary paths being located outside of the primary path and located on both one side and the other side of the primary path.
2. Description of the Related Art
In such an article transport facility, when an article transport location along the secondary path is specified as a transporting target for the article transport vehicle currently in the primary path, for example, after the article transport vehicle traveled along the primary path to the diverging location to the secondary path along which the article transport location specified as a transporting target exists, the article transport vehicle switches paths from the primary path to the secondary path, and travels along the secondary path to the stop position corresponding to the article transport location specified as the transporting target. And when an article transport location along another secondary path is specified as a transporting target for the article transport vehicle currently in the secondary path, after the article transport vehicle switched paths from the secondary path to the primary path, the article transport vehicle travels along the primary path to the diverging location to the secondary path along which the article transport location specified as a transporting target exists. Thereafter the article transport vehicle switches paths from the primary path to the secondary path, and travels along the secondary path to the stop position corresponding to the specified article transport location. Thus, the article transport vehicle travels to the stop position corresponding to the article transport location specified as a transporting target by switching paths from the primary path to the secondary path, and from the secondary path to the primary path.
An article transport location by a secondary path on the other side of the primary path is sometimes specified as a transporting target for an article transport vehicle in a secondary path on one side of the primary path. When that happens, the article transport vehicle would travel along the primary path after switching paths to the primary path and would have to travel along the loop-shaped primary path to the diverging location for the secondary path located on the other side of the primary path. Therefore, the article transport vehicle would have to cover a long distance, reducing article transporting efficiency and capacity.
To address this problem, a conventional article transport facility is provided with transporting conveyors for transporting articles between the secondary paths located on one side of the primary path and the secondary paths located on the other side of the primary path. When an article transport location by a secondary path on the other side of the primary path is specified as a transporting target for an article transport vehicle in a secondary path on one side of the primary path, the article is transferred from the article transport vehicle onto the transporting conveyor, and is transported by a transporting conveyor to the secondary path located on the other side of the primary path. And an article transport vehicle in the secondary path located on the other side of the primary path receives the article transported by the transporting conveyor, and travels to the stop position corresponding to the article transport location specified as a transporting target (see, for example, JP publication No. 2006-319154).
In the facility disclosed in the reference mentioned above, when transporting an article from an article transport location by the secondary path located on one side of the primary path to an article transport location by the secondary path located on the other side of the primary path, the article needs to be transferred from the article transport vehicle onto the transporting conveyor and another article transport vehicle needs to receive the article from the transporting conveyor, which takes time and slows down the article transporting process, which was problematic. And, in addition to the article transport vehicles, the transporting conveyor had to be provided, which lead to a complication of the configuration and raising cost.